Water preclusion system for watercraft exhaust

ABSTRACT

An exhaust system for a watercraft includes a water trap arranged on a first side of a hull tunnel, a discharge port arranged on a second side of the hull tunnel, and a chamber branched from and communicating with an exhaust passage connecting the watertrap with the discharge port.

PRIORITY INFORMATION

[0001] This application is based on and claims priority to JapanesePatent Application No. 10-296932 filed Oct. 19, 1998, the entirecontents of which is hereby expressly incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is directed to an exhaust system for awatercraft, and more particularly to a water preclusion and noiseattenuation system employed in a watercraft exhaust system.

[0004] 2. Description of Related Art

[0005] Personal watercraft have become very popular in recent years.This type of watercraft is quite sporting in nature and carries a riderand possibly one to three passengers. A relatively small hull of thepersonal watercraft commonly defines a riders' area above an enginecompartment. A two-cycle internal combustion engine frequently powers ajet propulsion unit which propels the watercraft. The engine lies withinthe engine compartment in front of a tunnel formed on the underside ofthe watercraft hull. The jet propulsion unit is located within thetunnel and is driven by a drive shaft. The drive shaft usually extendsbetween the engine and the jet propulsion device, through a wall of thehull tunnel.

[0006] Because of their small size and high degree of maneuverability,however, there are certain objections to the use of these watercraft onsome bodies of water. One of these objections is caused by the fact thatthis type of watercraft, primarily because of its small size, has arelatively simple exhaust system that does not provide a significantdegree of silencing. This result is mandated primarily by the verycompact nature of the watercraft and the relatively small area that isavailable for exhaust treatment. Because these watercrafts can beutilized on quite small bodies of water, the potential noise may be moreobjectionable than larger watercraft having unmuffled exhaust systemsbut which do not operate on these small bodies of water.

[0007] An exhaust system of a typical personal watercraft dischargesengine exhaust to the atmosphere either through or close to the body ofwater in which the watercraft is operating. Although submerged dischargeof engine exhaust silences exhaust noise, environmental concerns arise.These concerns are particularly acute in connection with two-cycleengines because engine exhaust from two-cycle engines often containslubricants, unburned fuel, and other byproducts.

[0008] Such environmental concerns have raised a desire to minimizeexhaustion of hydrocarbons and other exhaust byproducts (e.g., carbonmonoxide and oxides of nitrogen), and thus reduce pollution of theatmosphere and the body of water in which the watercraft is operated. Inresponse to the increased concerns regarding exhaust emissions, somepersonal watercraft engines recently have been equipped with a catalystto convert exhaust byproducts to harmless gases.

[0009] Catalysts must operate at a relatively high temperature in orderto produce the necessary thermal reaction and burning of the exhaustbyproducts. A catalytic device thus desirably operates within a specificrange of temperature so as to effectively and efficiently convert engineexhaust into generally harmless gases.

[0010] Some prior exhaust systems have employed a cooling jacket aboutthe catalytic device to maintain the catalytic device within the desiredtemperature range. In some systems, at least a portion of the coolingwater also is introduced into the stream of the exhaust gassesdischarged from the engine, not only further cool and silence theexhaust gases, but also to assist the discharge of exhaust gases. Theadded water to the exhaust system, however, gives rise to possibledamage to the catalyst.

[0011] In order to prevent water from entering the exhaust system whichcould therefore damage the engine and/or catalyst, it is been known toprovide watercraft with a device commonly referred to as a “watertrap”(a.k.a. “waterlock” or “water box”). A watertrap typically includes aninlet, an outlet, and a plurality of baffles defining open chamberswhich under certain operating conditions contain water. Typically, thewatertrap is arranged in the exhaust system downstream from the engineexhaust manifold and upstream from a discharge port of the exhaustsystem. The exhaust gases and water flow through the chambers within thewatertrap while the chambers generally prevent water from moving backthrough the watertrap and upstream through the exhaust system towardsthe engine exhaust manifold and/or the catalyst during abrupt watercraftmovements or if the watercraft is capsized. If a watercraft is capsized,a significant amount of water may flow into the watertrap from theportion of the exhaust system piping downstream from the watertrap,thereby forcing a substantial amount of water upstream into the exhaustsystem and fowling and/or damaging the internal combustion engine and/orshattering the catalyst bed of the exhaust system.

[0012] Exhaust noise also posses problems for personal watercraft use.Despite recent attempts to reduce the noise generated by and emissionsdischarged from personal watercraft powered by two-cycle engines,certain recreational facilities have banned the operation of two-cyclewatercraft. Such bans have resulted in a decrease in popularity ofpersonal watercraft powered by two-cycle engines.

SUMMARY OF THE INVENTION

[0013] A need exists for an exhaust system for a watercraft whichincludes a water preclusion system that further reduces the possibilityof water flowing upstream in the exhaust system during high speedoperation and/or capsizing, and which does not cause undue back pressurein the exhaust system which may reduce the power output of the engine ofthe watercraft. Additionally, it is desirable that such a system furtherattenuate exhaust noise and is compact in size, utilizing the relativelycompact spaces that are typically available in the hulls of personalwatercraft.

[0014] According to one aspect of the present invention, a watercraftincludes an exhaust system having an exhaust passage extending betweenan exhaust manifold of an engine and an exhaust discharge port providedon a first side of a hull tunnel of a hull of a watercraft. According tothe present aspect of the invention, the exhaust passage includes awatertrap device provided on a second side of the hull tunnel oppositethe first side and an intermediate portion extending between thewatertrap device and the discharge port. The intermediate portionextends above a top of the hull tunnel and includes a chamber branchedfrom and communicating with the intermediate portion. By providing achamber branched from and communicating with the intermediate portion ofthe exhaust passage, where the intermediate portion extends above a topof the hull tunnel of the watercraft, the present aspect of theinvention achieves the conflicting goals of preventing the upstream flowof water through the exhaust system while avoiding additional backpressure in the exhaust system.

[0015] For example, by providing the watertrap device on the side of thehull tunnel opposite the exhaust discharge port and providing thebranched chamber in the portion of the exhaust passage that extendsabove a top of the hull tunnel, the exhaust system provides anadditional chamber for trapping water that may flow into the exhaustdischarge port of the watercraft during high speed maneuvering orcapsizing. Furthermore, since the chamber is branched from theintermediate portion, the chamber does not generate large back pressuresin the exhaust system during operation of the internal combustionengine. Additionally, the branched chamber could optionally be tuned soas to form a Hemholtz resonator, so as to provide additional noisedampening of the internal combustion engine. Therefore, despite beingcapsized, the watercraft can adequately prevent permanent damage to theengine and/or catalyst bed, provide additional noise suppression ofexhaust, while avoiding the generation of additional back pressures inthe exhaust system.

[0016] Further aspects, features, and advantages of the presentinvention will become apparent from the detailed description of thepreferred embodiment which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above-mentioned and other features of the invention will nowbe described with reference to the drawings of a preferred embodiment ofthe present watercraft exhaust system. The illustrated embodiments ofthe watercraft are intended to illustrate, but not to limit theinvention. The drawings contain the following figures:

[0018]FIG. 1 is a partial sectional, side elevational view of a personalwatercraft including an exhaust system configured in accordance with apreferred embodiment of the present invention;

[0019]FIG. 2 is a top plan view of a portion of the exhaust systemincluded in the personal watercraft of FIG. 1;

[0020]FIG. 3 is a cross-sectional view along line 3-3 of the watercraftshown in FIG. 2;

[0021]FIG. 4 is a an enlarged perspective view of the exhaust systemshown in FIG. 2;

[0022]FIG. 5 is a top plan view of a chamber provided in the exhaustsystem shown in FIG. 4;

[0023]FIG. 6 is a sectional view along line 6-6 shown in FIG. 5;

[0024]FIG. 7 is a top plan view of the watercraft shown in FIG. 1schematically representing an arrangement of telltale ports;

[0025]FIG. 8 is a partial top plan view of the watercraft shown in FIG.1;

[0026]FIG. 9 is a rear elevational view of the control mast of thewatercraft shown in FIG. 1;

[0027]FIG. 10 is a partial side elevational view of the watercraft shownin FIG. 1, illustrating the movement of a hatch; and

[0028]FIG. 11 is a partial prospective view of the watercraft shown inFIG. 1 with the hatch in an open position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029] An improved exhaust system for a watercraft is disclosed herein.The exhaust system includes an enhances noise attenuation and waterpreclusion system which does not significantly increase backpressurewithin the system. Thus, engine performance is not significantlyimpacted despite quieter watercraft operation.

[0030]FIG. 1 illustrates a personal watercraft 10 which includes anexhaust system 12 configured in accordance with a preferred embodimentof the present invention. Although the present exhaust system 12 isillustrated in connection with a personal watercraft, the illustratedexhaust system can be used with other types of watercraft as well, suchas, for example, but without limitation, small jet boats and the like.Before describing the exhaust system 12, an exemplary personalwatercraft 10 will first be described in general details to assist thereader's understanding of the environment of use and the operation ofthe exhaust system 12.

[0031] The watercraft 10 includes a hull 14 formed by a lower hullsection 16 and an upper deck section 18. The hull sections 16, 18 areformed from a suitable material such as, for example, a moldedfiberglass reinforced resin (e.g., SMC). The lower hull section 16 andthe upper deck section 18 are fixed to each other around the peripheraledges 20 in any suitable manner.

[0032] As viewed in the direction from the bow to the stem of thewatercraft, the upper deck section 18 includes a bow portion 19, acontrol mast 20 and a rider's area 22. The bow portion 19 slopesupwardly toward the control mast 20 and includes at least one air ductthrough which air can enter the hull. A hatch cover 24 desirably extendsabove an upper end of the air duct to inhibit an influx of water intothe hull.

[0033] The hatch cover 24 is preferably attached to the upper decksection 18 via a hinge 25. Additionally, as shown in FIGS. 8, 10 and 11,pneumatic cylinders 27 are mounted adjacent the hinge 25 so as to biasthe hatch 24 to an open position, thereby enabling a user to easily openthe hatch 24. Furthermore, by providing two pneumatic cylinders 27, thehatch 24 can be raised, lowered and maintained in an open position in astable manner. The cylinders 27 also inhibit twisting of the hatch andthereby strengthen the hinged coupling. Also as shown in FIG. 11, thehatch 24 provides access to a access hole 29 which may be used toprovide access to a storage compartment for storing a fuel tank or anyother desired item.

[0034] A fuel tank (not shown) is preferably located within the hull 14beneath the hatch over 24. Conventional means, such as, for example,straps, are preferably used to secure the fuel tank to the lower hull16.

[0035] The control mast 20 extends upward from the bow portion 19 andsupports a handlebar assembly 28. The handlebar 28 controls the steeringof the watercraft 10 in a conventional manner. The handlebar assembly 28also carries a variety of controls of the watercraft 10, such as, forexample, a throttle control, a start switch and a lanyard switch.

[0036] A display panel (not shown) is desirably located in front of thecontrol mast 20 on the bow portion 19 and is orientated to be visible bythe rider. The display panel desirably displays a number of performancecharacteristics of the watercraft such as for example, watercraft speed(via a speedometer), engine speed (via a tachometer), fuel level, oillevel, engine temperature, battery charge level and the like. As shownin FIG. 8, the cowling adjacent the control mast 20 preferably includesa reverse lever 21 a, a fuel cock 21 b, and a choke 21 c. Thesecomponents are arranged to the sides of the control mast 20 and justforward of the same. The reverse lever 21 a is operatively connected toa conventional reverse thrust bucket (not shown) which is configured toselectively divert water discharged from a propulsion device to causethe watercraft 10 to move in a reversed direction. The fuel cock 21 band choke knob 21 c are arranged on a side of the control mast 20opposite the reverse lever 21 a. This arrangement of these componentsdisposes each of them in convenient reach of the watercraft rider whenseated just behind the control mast 20..

[0037] The rider's area 22 lies behind the control mast 20 and includesa seat assembly 30. In the illustrated embodiment, the seat assembly 30has a longitudinally extending straddle-type shape that may be straddledby an operator and by at least one to three passengers. The seatassembly 30, at least in principal part, is formed by a seat cushion 32supported by a raised pedestal 34. The raised pedestal 34 has anelongated shape and extends longitudinally along the center of thewatercraft 10. The seat cushion 32 desirably is removably attached to atop surface of the pedestal 34 and covers the entire upper end of thepedestal for rider and passenger comfort.

[0038] An access opening (not shown) is preferably located on an uppersurface of the pedestal 34. The access opening opens into an enginecompartment 38 formed within the hull 14. The seat cushion 32 normallycovers and seals an access opening 35. When the seat cushion 32 isremoved, the engine compartment 38, as well as a storage cavity 36, areaccessible through the access opening.

[0039] The pedestal 34 also desirably includes at least one air duct(not shown) located behind the access opening. The air duct communicateswith the atmosphere through a space formed between the pedestal 34 andthe cushion 32, which is formed behind the access opening. Air can passthrough the rear duct in both directions.

[0040] As shown in FIGS. 3 and 8, the upper deck section 18 of the hull12 advantageously includes a pair of raised gunnels 39 positioned onopposite sides of the aft end of the upper deck assembly 18. The raisedgunnels 39 define a pair of foot areas 40, as shown in FIG. 8, thatextend generally longitudinally and parallel to the sides of thepedestal 34. In this position, the operator and any passengers sittingon the seat assembly 30 can place their feet in the foot areas 40 withthe raised gunnels 39 shielding the feet and lower legs of the riders. Anon-slip (e.g., rubber) mat desirably covers the foot areas 40 toprovide increased grip and traction for the operator and the passengers.

[0041] The lower hull portion 16 principally defines the enginecompartment 38. Except for the air ducts, the engine compartment 38 isnormally substantially sealed so as to enclose an engine of thewatercraft 10 from the body of water in which the watercraft isoperated.

[0042] The lower hull 16 is designed such that the watercraft 10 planesor rides on a minimum surface area at the aft end of the lower hull 16in order to optimize the speed and handling of the watercraft 10 when upon plane. For this purpose, as shown in FIG. 3, the lower hull sectiongenerally has a V-shaped configuration formed by a pair of inclinedsections that extend outwardly from a keel line 16 a of the hull to thehull's side walls at a dead rise angle. Each inclined section desirablyincludes at least one strake 16 c, and the strakes 16 c of the hullpreferably are symmetrically disposed relative to the keel line of thewatercraft 10. The inclined sections also extend longitudinally from thebow toward the transom of the lower hull 14. The side walls aregenerally flat and straight near the stem of the lower hull and smoothlyblend towards the longitudinal center of the watercraft at the bow. Thelines of intersection between the inclined sections and thecorresponding side walls form the outer chines 16 b of the lower hullsection.

[0043] Toward the transom of the watercraft, the inclined sections ofthe lower hull 16 extend outwardly from a recessed channel or tunnel 42that extends upward toward the upper deck portion 16. As usedhereinafter, “recessed channel,” “tunnel,” and “hull tunnel” are usedinterchangeably to refer to the portion of the transom end of thewatercraft hull that is formed to accommodate a jet of water generatedby the watercraft for propulsion purposes. For example, the watercraft10 includes a jet pump unit 44 which generates a generally rearwarddirected jet of water to generate a propulsion force to cause forwardand/or reverse movement of the watercraft 10.

[0044] The jet pump unit 44 is mounted within the tunnel 42 formed onthe underside of the lower hull section 16 by a plurality of bolts. Anintake duct of the jet pump unit 44 defines an inlet opening 45 thatopens into a gullet. The gullet leads to an impeller housing assembly inwhich the impeller of the jet pump 44 operates. An impeller housingassembly also acts as a pressurization chamber and delivers the waterflow from the impeller housing to a discharge nozzle housing.

[0045] A steering nozzle 46 is supported at the downstream end of adischarge nozzle 48 by a pair of vertically extending pivot pins. In anexemplary embodiment, the steering nozzle 46 has an integral lever onone side that is coupled to the handlebar assembly 28, for example, abowden-wire actuator, as known in the art. In this manner, the operatorof the watercraft can move the steering nozzle 46 to effect directionalchanges of the watercraft 10.

[0046] A ride plate 50 preferably covers a portion of the tunnel 42behind the inlet opening 45 to enclose the pump assembly and a nozzleassembly 60 of the propulsion unit. The aft end of an impeller shaft 52is suitably supported and journaled within the engine chamber of theassembly in a known manner. The impeller shaft 52 extends in the forwarddirection through a front wall 54 of the tunnel 42 as well as through abulkhead 56.

[0047] An internal combustion engine 60 of the watercraft powers theimpeller shaft 52 to drive the impeller of the jet pump unit 44. Theengine 60 is positioned within the engine compartment 38 and is mountedprimarily beneath the control mast 20. Vibration-absorbing engine mounts(not shown) are preferably used to secure the engine 60 to the lowerhull portion 16 in a known manner. The engine 60 is mounted inapproximately a central position in the watercraft 10.

[0048] In the illustrated embodiment, the engine 60 includes threein-line cylinders and operates on a two-stroke, crankcase compressionprinciple. The engine 60 is positioned such that the row of cylinderslies parallel to a longitudinal axis of the watercraft 10, running frombow to stern. The axis of each cylinder may be skewed or inclinedrelative to a vertical central plane of the watercraft 10, in which thelongitudinal axis lies. This engine type, however, is merely exemplary.Those skilled in the art will readily appreciate that the presentexhaust system can be used with any of a variety of engine types havingother number of cylinders, having other cylinder arrangements andoperating on other combustion principles (e.g., four-stroke principle).

[0049] Preferably, the jet pump 44 supplies cooling water through aconduit (not shown) to an engine cooling jacket. For this purpose, anoutlet port may be formed on the housing of the jet pump 44. The conduitis coupled to an outlet port and extends to an inlet port for supplyingcoolant, such as water to the engine cooling jacket. The engine coolingjacket extends through the exhaust manifold, through the cylinder block,about the cylinders, and through the cylinder head assembly. Either thecylinder head assembly or the exhaust manifold can include a coolantdischarge port through which the cooling water exits the engine 60 andthence flows through at least a portion of the exhaust system 12.

[0050] The personal watercraft 10 so far described represents only anexemplary watercraft on which the present exhaust system 12 can beemployed. A further description of the personal watercraft 10 is notbelieved necessary for an understanding and an appreciation of thepresent exhaust system 12. The exhaust systems will now be described indetail.

[0051] The exhaust system 12 discharges exhaust byproducts from theengine 60 to the atmosphere and/or to the body of water in which thewatercraft 10 is operated. The exhaust system 12 is fed exhaust gassesfrom an exhaust manifold (not shown) that is affixed to the side of thecylinder block of engine 60 and which receives exhaust gases from thecombustion chambers through exhaust ports in a well-known manner. Forthis purpose, the exhaust manifold desirably includes a number ofrunners equal in number to the number of cylinders. Each runnercommunicates with the exhaust port(s) of the respective cylinder. Therunners of the exhaust manifold thence merge together to form a commonexhaust path that terminates at an outlet end of the manifold.

[0052] The exhaust manifold may have a dual shell construction formed byan inner wall and an outer wall. A cooling jacket is formed between thetwo walls and communicates with one or more water passages within theengine block 60. In the illustrated embodiment, coolant flows from theengine block 60 into the cooling jacket of the exhaust manifold; suchcoolant, however, can be supplied from a different location of thecooling system (e.g., from a location upstream of the engine coolingjacket). This dual wall construction desirably is formed along eachrunner of the manifold, as well as about the common flow section of themanifold.

[0053] As shown in FIG. 7, an expansion chamber 72 has a generallytubular shape with an enlarged cross-sectional flow area to allow theexhausts gases to expand and silence, as known in the art. The upstreamend of the expansion chamber 72 has a diverging configuration and thedownstream has a converging configuration, as is conventional. Athick-wall, which is defined between an inner surface and an outersurface forms the tubular shape of the expansion chamber 72. The innersurface defines the exhaust flow passage through the expansion chamber72. A plurality of cooling passages (not shown) extend along side theflow passage through the thick wall of the expansion chamber 72. Thepassages are desirably spaced around the inner surface.

[0054] As shown in FIG. 1, the expansion chamber 72 has a reducedcross-sectional outlet portion 74 which directs exhaust gases into acatalytic device 76. The catalytic device 76 desirably includes thecatalyst bed 78 which changes at least a portion of the exhaust gasesinto harmless gases (e.g., carbon dioxide and water). The catalyst bed78 lies within the exhaust gas flow through the exhaust system 12 at aposition that mandates that all exhaust gases must pass through thecatalyst bed 78. The catalyst bed 78 reduces the emissions ofhydrocarbons and other exhaust products (e.g., carbon monoxide andoxides of nitrogen) from the watercraft engine.

[0055] For this purpose, the catalyst bed 78 is formed of a catalyticmaterial, which is designed to render harmless either all or some of theexhaust byproducts. For example, the catalyst bed 78 can be made of ametal catalyst material, such as, for example, platinum. The catalystbed 78, however, can be made of different types of catalytic materialsfor treating different exhaust byproducts or lubricants.

[0056] The catalyst device 76 is jacketed by a cooling jacket. In theillustrated embodiment, the cooling jacket receives coolant flow fromthe cooling jacket in thermal contact with the expansion chamber. Othercoolant flow path arrangements of course are also possible, as wellknown in the art.

[0057] As shown in FIG. 1, an exhaust passage 68 extends downwardly fromthe catalytic device 76 and is coupled to a watertrap device 80 by aflexible conduit.

[0058] As shown in FIGS. 1 and 2, the watertrap 80 is connected to theexhaust passage 68 via a connector pipe 82. Preferably, the watertrapdevice 80 is provided with a plurality of internal baffles arranged toretain a predetermined volume of water and to generally suppress theback flow of water toward the catalytic device 76. In order to furtherinhibit significant flows of water into the watertrap 80 during highspeed maneuvering or capsizing, the watercraft 10 is provided with awater preclusion system 90.

[0059] The present water preclusion system 90 inhibits a flow ofsignificant volume of water through watertrap 80, and into the catalyticbed 78 and/or the expansion chamber 72. As noted above, if water reachesthe catalytic bed 78 during operation of the watercraft 10, thecatalytic bed 78 can shatter under some operating condition.Additionally, if water, especially sea water, enters the expansionchamber 72, the exhaust manifold or the combustion chambers of theengine 60, accelerated and/or severe corrosion can occur which oftenrequires expensive and invasive repairs. The present water preclusionsystem 90 thus inhibits a significant backflow of water through theexhaust system and thereby reduces the likelihood that such repairs tothe catalyst device, to the engine, and/or to the balance of the exhaustsystem will be required.

[0060] As shown in FIGS. 1 through 4, the water preclusion system 90includes an intermediate exhaust passage 92 which extends between thewatertrap device 80 and an exhaust discharge 94. Although the passage 92may be formed monolithically with chambers 100 and 110 (discussed indetail below), the passage 92 is preferably formed of portions 91, 93,and 95, which are constructed from an appropriate material, such as, forexample, high temperature rubber or plastic. Depending on whichcomponents are included in the system 90, portions 91, 93, and 95, orvarious combination thereof, are connected via couplings 97 in an knownmanner.

[0061] As shown in FIG. 3, the watercraft 10 floats, in an unloadedstate, such that the water line is approximately at the level of anunloaded water line 96. When the watercraft 10 is loaded with themaximum rated weight, the watercraft 10 floats at a depth ofapproximately the maximum rated water line 98. As shown in FIG. 3, theintermediate exhaust passage 92 extends from the watertrap device 80 ata position below the maximum rated water line 98 above the tunnel 42,and to a position above the maximum rated water line 98, then to aposition below the water line 98 and the water line 96 to discharge theport 94. Therefore, when the watercraft 10 is at rest with the maximumrated load, water will flow into the exhaust discharge 94 and up intothe intermediate passage 92 only up to the water line 98. Therefore, atleast when the watercraft 10 is at rest with the maximum rated load,water should not flow into the watertrap 80.

[0062] However, as shown in FIGS. 1-4, the water preclusion system 90includes the chamber 100 which is branched from and communicates withthe intermediate passage 92. As shown in the figures, the chamber 100communicates with the passage 92 via a throat 104. Preferably, thechamber 100 is in the form of a tuned resonator chamber 102 configuredto form a Hemholtz resonator with the throat portion 104, so as toattenuate noise from the engine 60. As shown in FIG. 3, the chamber 100is arranged so as to communicate with the intermediate passage 92 at aposition above the tunnel 42 and/or above the maximum rated water line98. As an example, the intermediate passage 92 may be formedmonolithically with the chamber 100, or, as shown in the figures, theintermediate passage may be formed with the detachable portions 91, 93,and 95 formed of high temperature rubber or plastic and connected viathe couplings 97. In this embodiment, the portion 91 connects awatertrap outlet 80 b with an inlet 100 a, and the portion 93 connectsan outlet 100 b with an discharge port inlet 94 a.

[0063] As shown in FIGS. 3 and 4, the chamber 100 preferably extendsupwardly from the intermediate passage 92. If the watercraft 10 iscapsized, thereby causing water to flow towards an apex 106 of theintermediate passage 92, as viewed in FIG. 3, the water will flow intothe chamber 100 and will be stored there at least temporarily while thewatercraft 10 remains capsized, thereby preventing the water fromflowing directly into the watertrap 80.

[0064] The chamber 100 preferably communicates with the intermediatepassage 92 at a position downstream from the apex 106 of theintermediate passage 92. Arranged as such, the chamber 100 will tend todirect water, which flowed into the chamber 100 during the capsizing ofthe watercraft 10, downstream from the apex 106 towards the exhaustdischarge port 94 after the watercraft 10 has been righted. Therefore,even if the watercraft 10 is capsized with a significant amount of waterin the intermediate passage 92, the chamber 100 will temporarily storeand return water to the portion of the intermediate passage 92 which isdownstream from the apex 106. By providing the chamber 100 as such, thewater preclusion system 90 achieves the dual goals of preventing adamaging back flow of water in the exhaust system of a watercraft, andavoiding the power sapping back pressure in the exhaust system.Furthermore, if the chamber 100 is tuned so as to form a Hemholtzresonator with the throat portion 104, the system 90 additionallyreduces the noises generated by the engine 60 without a significantincrease in backpressure.

[0065] The water preclusion system 90 may, in addition or in lieu of thechamber 100, include the chamber 110 which communicates with theintermediate passage 92 via an inlet 112 and an outlet 114. As shown inFIG. 3, the chamber 110 has a cross-sectional area that is larger than across sectional area of the intermediate passage 92, by virtue of itselongation generally in a horizontal direction. Preferably, a connector116 extends into the reservoir 110 a predetermined distance 118. Asshown in FIG. 6, the connector 116 is preferably formed monolithicallywith the reservoir 110. However, it is conceived that the connector 116may be formed separately and sealably engaged with the reservoir 110.With the chamber 110 included in the intermediate passage 92, the inlet110 a of the chamber 110 preferably communicates with the intermediatepassage 92 via the portion 93 while the chamber 100 and the outlet 110 bis connected to discharge the inlet 94 a.

[0066] As shown in FIG. 6, the reservoir 110 includes a lower surface120 and an upper surface 122. Preferably, the chamber 100 is arrangedsuch that the maximum rated water line 98 falls below the upper surface122. Therefore, a volume of water fills the chamber 110 up to the waterline 98 when the watercraft is loaded with its maximum rated load.

[0067] Preferably, the chamber 110 and the predetermined distance 118are configured such that when the chamber 110 is inverted, such as whenthe watercraft is capsized, the volume of water urged into the chamber110 when the watercraft 10 is loaded with its maximum rated load, fillsthe inverted chamber 110 to a depth equal to or less than thepredetermined distance 118. Therefore, when the watercraft 10 iscapsized, the volume of water trapped within the chamber 110 is notsufficient to flow upstream the past inlet 112. However, it is to benoted that, depending on the events leading to capsizing, more or lesswater may actually be trapped in the exhaust passage 92 when thewatercraft 10 is capsized. However, with the chamber 110 and thepredetermined distance 118 configured as such, it has been found that asufficient amount of water can be prevented from causing a damaging backflow of water from occurring.

[0068] Furthermore, if the chamber 110 is used in conjunction with thechamber 100, the chamber 100 may trap any water that may flow past theinlet 112 during capsizing of the watercraft 10. Therefore, by providingthe chamber 100 and the chamber 110 to the intermediate portion 92, theexhaust system prevents damaging upstream flow of water that hasheretofore plagued personal watercraft. Additionally, if the chambers100 and 110 are provided together, further tuning, in a known manner, ofthe chambers 100 and 110, can produce additional attenuation of enginenoise.

[0069] According to a further aspect of the present invention, awatercraft, such as the watercraft 10, is provided with at least twotelltale ports configured to discharge a stream of water to a positionforward of the rider's seating area. For example, as shown in FIG. 7,the internal combustion engine 60 includes the exhaust passage 68 whichis connected to an exhaust manifold (not shown) at a first end and to awater trap (not shown) at a second end. In order to provide a desiredcooling of the exhaust passage 68, a cooling jacket 69 is formed aroundthe exhaust passage 68. A first portion 71 of the cooling jacket 69 isfed with a coolant from a cooling jacket formed in the engine 60 viarunners 73.

[0070] As shown in FIG. 7, the first portion 71 of the cooling jacket 69is configured to circulate coolant in thermal contact with the expansionchamber 72. Preferably, the expansion chamber 72 is constricted at theportion 74. Downstream from the portion 74, the expansion chamber 72 iscoupled to a downstream portion 75 of the exhaust passage 68. Thedownstream portion 75 may include a catalytic device such as thecatalyst bed 78 for removing pollutants from the exhaust gases in aknown manner. As noted above, the cooling jacket 69 extends over thedownstream portion 175 of the exhaust passage 68 to cool the catalyticbed 78. Communication between the first portion 71 of the cooling jacket69 and the downstream portion 75 is accomplished through a knowncoupling between the portion 71 and the portion 75.

[0071] Although it has been known to provide a telltale port on awatercraft in order to verify that coolant is flowing through theappropriate cooling jackets and channels of the engine and the exhaustsystem, it has been found that a leak or a blockage may be caused atvarious places within a cooling jacket which may not cause a change inthe appearance of the telltale stream sufficient to capture theattention of the user. Therefore, the watercraft 10 is preferablyprovided with at least two telltale ports configured to discharge astream of coolant from the cooling jackets 69.

[0072] As shown in FIG. 7, the telltale ports 120, 122 are arranged at aposition forward of the handle bar 28. As is apparent from FIG. 7, thetelltale ports 120, 122 are arranged as sufficiently forward of thehandle bar 28 so as to be clearly visible to a user seated in therider's seating position 22.

[0073] The telltale ports 120 and 122 are connected to the coolingjacket 69 via conduits 124, 126, respectively. Arranged as such, thetelltale ports 120, 122 are clearly visible to a user seated in therider's seating area 22 regardless of whether a user is looking towardthe user's left or toward the user's right. Therefore, the user will beapprised at all times of the operating condition of the cooling systemof the watercraft 10.

[0074] One of the telltale ports 120,122 preferably is connected to thecooling jacket 69 at a position 128 which is upstream from a position130 at which the other of the telltale ports 120, 122 is attached to thecooling jacket 69. For example, the positions 128, 130 may be spaced bya distance 132. Preferably, the position 128 is provided on an upstreamside of the coupling between the portion 71 and the downstream portion75 while the position 130 is provided downstream of the coupling.Arranged as such, a user is provided with an indicator of the coolantpressure in two distinct portions of the cooling jacket 69. For example,when a user is operating the watercraft 10, the telltale streams of thecoolant are continuously discharged from the ports 120, 122. However, ifa leak forms, for example, in the coupling between the upstream portion71 of the cooling jacket 69 and in the downstream portion 75, thetelltale stream discharged from the port 122 will become weaker ornon-existent. Therefore, by comparing the appearance of the waterstreams discharged from the ports 120, 122, a user can identify a leakin the cooling system. This is particularly useful since the exhaustsystems of watercrafts, and in particular, those systems that include acatalytic device, operate at high temperature which should be controlledto a particular operating range. Therefore, by providing the user with areference for detecting a leak in an early stage, severe damage to thecatalytic bed and to other components of the watercraft can beprevented. This arrangement provides an improvement over a system with asingle telltale port. For example, if a watercraft such as thewatercraft 10 is provided only with the telltale port 122, a user cannot determine that a blockage in the exhaust system has occurreddownstream of the point of the cooling system to which the telltale portis connected. Thus, the user can not determine that coolant flow to acritical component (e.g., a catalyst device) is diminished or stopped.In contrast, by providing at least two telltale ports 120, 122, a usercan readily view the two telltale streams and proper coolant flow withinthis critical section of the cooling system.

[0075] Although this invention has been described in terms of a certainpreferred embodiment, other embodiments apparent to those of ordinaryskill in the art are also within the scope of this invention.Accordingly, the scope of the invention is intended to be defined onlyby the claims that follow.

What is claimed is:
 1. A watercraft having a hull defining an enginecompartment in which an engine is provided, said engine including atleast one exhaust port for discharging exhaust gases from said engine tothe atmosphere through an exhaust system, said exhaust system comprisingan exhaust passage extending between an exhaust manifold of said engineand an exhaust discharge port provided on a first side of a hull tunnelof said hull, said exhaust passage including a watertrap device providedon a second side of said hull tunnel opposite said first side, saidexhaust passage including an intermediate portion extending between saidwatertrap device and said discharge port, said intermediate portionextending above a top of said hull tunnel, and a first chamber branchedfrom and communicating with said intermediate portion.
 2. A watercraftas in claim 1, wherein said first chamber branches upwardly from saidintermediate portion.
 3. A watercraft as in claim 1, wherein said firstchamber is provided at a position above said hull tunnel.
 4. Awatercraft as in claim 3, wherein said first chamber is provided at aposition downstream from an apex of said intermediate portion.
 5. Awatercraft as in claim 1, wherein said intermediate portion includes athroat provided between said first chamber and said intermediateportion, through which said first chamber and said intermediate portioncommunicate, and said throat and said chamber being tuned so as to forma Hemholtz resonator to attenuate noise from said engine.
 6. Awatercraft as in claim 5, wherein said throat and said Hemholtzresonator are arranged so as to branch upwardly from said intermediateportion.
 7. A watercraft as in claim 1, additionally comprising a secondchamber communicating with said intermediate portion at a positionbetween said first chamber and said discharge port, said first chamberhaving a cross-sectional area larger than a cross-sectional area of saidintermediate portion.
 8. A watercraft as in claim 7, wherein said firstchamber branches upwardly from said intermediate portion, and whereinsaid second chamber comprises a cavity elongated in a substantiallyhorizontal direction.
 9. A watercraft as in claim 8, wherein saidintermediate reservoir is arranged such that a maximum rated water lineof said watercraft loaded with a maximum rated load is below an upperwall of said second chamber.
 10. A watercraft as in claim 9, whereinsaid intermediate portion includes a connector portion extending apredetermined length into an interior of said second chamber.
 11. Awatercraft as in claim 10, wherein said second chamber and saidpredetermined length are configured such that an amount of watersufficient to fill said second chamber to the maximum rated waterline isnot sufficient to flow past said connector portion when said watercraftis inverted.
 12. A watercraft as in claim 10, wherein said intermediateportion includes a throat provided between said chamber and saidintermediate portion, through which said chamber and said intermediateportion communicate, said throat and said first chamber being tuned soas to form a Hemholtz resonator and to attenuate noise from said engine,and said connector portion and said Hemholtz resonator being tuned so asto provide sound attenuation of the exhaust of said engine.
 13. Awatercraft as in claim 1, additionally comprising a cooling jacketconfigured to circulate a coolant in thermal communication with saidexhaust passage, a first telltale port and a second telltale portconfigured to discharge a stream of the coolant at a position forward ofan operator's seating position of said watercraft, said first telltaleport communicating with said cooling jacket at a position upstream fromsaid second telltale port.
 14. A watercraft as in claim 13, wherein saidexhaust passage additionally comprises an expansion chamber portionincluding an expansion chamber and a downstream portion communicatingwith said expansion chamber portion through an exhaust passage coupling,and extending downstream from said expansion chamber portion, saidcooling jacket including a first portion in thermal communication withsaid expansion chamber portion and a second portion in thermalcommunication with said downstream portion, said first and secondportions of said cooling jacket fluidically communicating through saidexhaust passage coupling, said first telltale port communicating withsaid first portion of said cooling jacket and said second telltale portcommunicating with said second portion of said cooling jacket.
 15. Awatercraft having a hull defining an engine compartment in which anengine is provided, said engine including at least one exhaust port fordischarging exhaust gases from said engine to the atmosphere through anexhaust system, said exhaust system comprising an exhaust passageextending between an exhaust manifold of said engine and an exhaustdischarge port provided on a first side of a hull tunnel of said hull,said exhaust passage including a watertrap device provided on a secondside of said hull tunnel opposite said first side, said exhaust passageincluding an intermediate portion extending between said watertrapdevice and said discharge port, said intermediate portion extendingabove a top of said hull tunnel, and a first chamber communicating withsaid intermediate portion and having a cross-sectional area larger thana cross-sectional area of said intermediate portion, said first chamberprovided downstream of an apex of said intermediate portion, said firstchamber being disposed relative to a maximum rated water line of saidwatercraft such that an upper wall of said first chamber lies above saidmaximum rated waterline.
 16. A watercraft as in claim 15, wherein saidintermediate portion includes a connector portion extending apredetermined length into an interior of said first chamber.
 17. Awatercraft as in claim 16, wherein said first chamber and saidpredetermined length are configured such that an amount of watersufficient to fill said first reservoir to the maximum rated water lineis not sufficient to flow past said connector portion when saidwatercraft is inverted.
 18. A watercraft as in claim 16, furthercomprising a Hemholtz resonator branched from said intermediate portionat a position downstream from an apex of said intermediate portion. 19.A watercraft having a hull defining an operator's seating position andan engine compartment in which an engine is provided, said engineincluding at least one exhaust port for discharging exhaust gases fromsaid engine to the atmosphere through an exhaust system, said exhaustsystem comprising an exhaust passage extending between an exhaustmanifold of said engine and an exhaust discharge port, a cooling jacketconfigured to circulate coolant in thermal communication with saidexhaust passage, and first and second telltale ports configured todischarge streams of cooling jacket liquid at positions forward of theoperator's seating position of said watercraft.
 20. A watercraft as inclaim 19, wherein said exhaust passage additionally comprises anexpansion chamber portion including an expansion chamber and adownstream portion communicating with said expansion chamber portionthrough an exhaust passage coupling, and extending downstream from saidexpansion chamber portion, said cooling jacket including a first portionin thermal communication with said expansion chamber portion and asecond portion in thermal communication with said downstream portion,said first and second portions of said cooling jacket fluidiciallycommunicating through said exhaust passage coupling, said first telltaleport communicating with said first portion of said cooling jacket andsaid second telltale port communicating with said second portion of saidcooling jacket.
 21. A watercraft as in claim 19, wherein said first andsecond telltale ports are configured to discharge streams of coolant onopposite sides of said hull.